Conventional audio playback apparatus, such as a compact disk player, has the capability of sequentially playing a random sequence of pre-recorded audio tracks or cues. Thus, a plurality of recordings by the same artist or same composer or of audio-related material of various kinds can be randomly shuffled by the controller of the disk player and then played for the listener. This technology can also be used for the random sequential playing of video disk tracks, although such capability is not in such wide-spread use.
The sequential playback of pre-recorded audio or video works, however, has been limited to the sequential playing of a plurality of discrete compositions, rather than the generation of an integrated or continuous composite composition from the pre-recorded works. Thus, in prior art systems one complete musical composition is played and then another one is randomly selected and played. No attempt is made to form a unitary, although composite, musical work from two or more pre-recorded tracks.
One area in which pre-recorded audio compositions have been extensively used is in connection with public displays of the type found in museums, entertainment facilities and trade shows. Thus, a diorama illustrating the habitat of a particular group of animals also may include recordings of the voices of these animals in their natural habitat or environment. Most typically, the recordings played at such public exhibitions will be created by a sound engineer who overlays and mixes a plurality of individual recorded tracks to form a single recording that can be played for visitors of the diorama. A single track of, for example, fifteen minutes can be used to illustrate the various voices of the inhabitants of the diorama, and the visitors will have an experience which is substantially enhanced over merely the visual impact of the diorama. Museum personnel, however, will hear the diorama recording over and over during the course of the day to the point that the repeating sequencing of even a fifteen minute track becomes aggravating.
Several types of enhancements have been provided for the museum-type, repeating, audio delivery systems. First, infrared sensors have been used to sense the density or number of people listening to the audio program and to adjust the volume. When more listeners are present, the volume will be shifted toward a high volume setting, while the absence of sensed listeners reduces the volume. Second, sensors also have been used to trigger a pre-recorded audio sound so that when a listener walks in front of a sensor a sound track or sound cue is played. The first of these enhancements does not affect the monotony of repetition, and the second only has the minor impact of adding an event-driven sound to the overall audio playback.
Another enhancement which has been employed is to pan or move the sound being played over the plurality of spaced apart speakers in a speaker system. Thus, a rain storm can be heard first at one end of the diorama and then gradually move or pan through the speaker system to the opposite end. This type of enhancement similarly does not eliminate the redundancy of repetition, and the pans or moves of the sound merely become part of the repeating pattern.
It is also known in the music industry to create musical compositions by computer-controlled apparatus. Thus, a music synthesizer can be controlled by a computer in a manner used to generate a musical composition, but the generation of such audio or musical works is not based upon pre-recorded material, but instead on the synthesis of music as controlled by music composition software.